Routers have become a popular tool in woodworking due to the flexibility of the tool allowing it to carry out a number of different functions. This flexibility has been particularly enhanced by providing a router table with an upper surface on which the workpiece can be located and moved so as to move relative to the fixed router and the router bit which projects through the surface.
Routers therefore are commonly used with a router table and in many cases the router table includes an insert plate which is bolted onto the end plate of the router so that the drive shaft of the router projects through an opening in the plate to the router bit which is presented wholly or partly above the surface to act upon the workpiece. Different arrangements of bits can be used for different functions.
In some cases the router is used to cut a groove in the under surface of the workpiece with the groove being shaped in dependence upon the shape of the bit for various different arrangements and uses.
In other functions, the bit is used to cut or shape an edge of the workpiece. In this case the workpiece can be guided by a fence mounted on the table at the bit. Other arrangements of guide fence are well known to one skilled in the art for co-operation with various guide elements which can be attached to the workpiece or to the table.
Routers can also be used as hand held or manual tools where the workpiece is clamped to the table and the router bit moved over the workpiece. The bit axis is maintained at right angles to the workpiece surface by providing a router end plate lying in a radial plane of the bit so that the bottom surface of the end plate can slide over the workpiece in contact with the upper surface thereof.
One problem area which remains in such routers, despite many years of development and availability, is that of removing the machined waste material in the form of dust or chips which can be expelled into the air or left as waste material on the table or on the workpiece.
This problem has been sufficiently severe to limit the desirability of this machining method since the material expelled into the air is difficult to control and can be at best unpleasant and at worst environmentally damaging.
Various attempts have therefore been made to extract the dust and particles from the area of the workpiece including overhead suction nozzles which are attached to a suction duct. Such suction nozzles can be adjusted and located at a suitable position so as to attempt to carry away the dust and particles expelled by the bit in an upward direction away from the table. This arrangement is unsatisfactory in that it is unable to collect all of the materials escaping into the air and in that it often leaves materials on the table which interfere with the operation and movement of the workpiece, or it leaves materials on the workpiece which interfere with the movement of the hand held router.
Another arrangement has been provided to generate suction around the bit at the bit opening in the table. This is normally provided by generating a suction duct in the end plate of the router. Thus the end plate around the motor is machined with various walls and dividers in the end plate it is clamped to the underside of the table so as to generate a suction around the bit opening to attempt to extract material which is released at the bit into the end plate of the router and from that end plate into a suction nozzle attached to the router itself. This arrangement has become widely and commonly accepted in the router industry and many routers are currently available with such a suction extraction system. However the system has been revealed to be less than satisfactory leaving many particles on the table and still allowing dust to expel into the air.
Up until now there has been no simple solution to problem of waste material extraction and this remains and has remained a long standing problem.
In an article in the Journal Better Homes and Gardens WOOD of February 1999 Issue No. 33 pages 50 to 56 is shown an arrangement in which a suction duct is communicated to an opening on the router table which is spaced away from the router bit at a position which is intended to be behind the guide fence so that suction across the top of the table surfaces communicated from the suction opening to the router bit between the two sections of the fence by a cover over a top of the table. This arrangement is merely a proposal in a magazine and has not apparently led to any commercial production.
In U.S. Pat. No. 5,611,378 (Brazell) issued Mar. 18, 1997 is disclosed an arrangement in which a suction duct is communicated through a slot in the underside of the table to the area of the bit so as to attempt to remove the particles from the area of the bit. This arrangement is also unsatisfactory.
A further problem with regard to the base plate for an arrangement of this type is that of the attachment of the base plate to the router. Many different styles of router are manufactured by many different companies so that each has an end plate on the router body with a different pattern of fasteners. This makes it very difficult to provide a universal base plate which can be attached to all different types of router in view of the complexity of the different hole patterns.
Some manufacturers overcome this problem by manufacturing a number of different plates each with different hole patterns and each designed to attach to particular routers of particular manufacturers. However this is of course inconvenient and there is a significant risk that the purchaser will obtain the wrong plate for the wrong router leading to frustration.
Some plates are simply manufactured without holes leaving the purchaser to drill holes at the required location. However placing these holes at the required position is extremely difficult to achieve any effective attachment let alone an accurate attachment which locates the hole in the base plate concentric with the axis of the bit.
Attempts to overcome this problem have been put forward by JessEm Tool Company of Ontario Canada in their brochure for the product “Mast R Plate” and “Route R Plate”. These arrangements are shown in U.S. Pat. No. 6,520,224 (Smith) issued Feb. 18, 2003. In these arrangements there is provided a mounting plate which has either a large array of holes or has slots which is thus highly perforated together with a cover plate which attaches on top of the mounting plate and forms the top surface for the base plate in the table. This arrangement has been commercially available but has some difficulty in that it requires additional parts with the prospect of increased complication and increased cost.
In U.S. Pat. No. 6,382,276 (Daniels) issued May 7, 2002 the same problem is considered and the solution uses an intervening mounting plate which is again highly perforated with whole arrays of a particular complexity.
U.S. Pat. No. 6,305,447 discloses a further arrangement of base plate which utilizes central rings within a central opening of the base plate so as to define a required diameter of a central opening, depending upon the ring selected.